罕見後腎腺瘤--案例報告
陳嘉宏1、張延驊1,2,3、林登龍1,2,3、陳光國1,2,3
台北榮民總醫院 泌尿部1；國立陽明大學醫學院 泌尿學科2書田泌尿科學研究中心3
Metanephric adenoma of the kidney - a case report and literature review
Chia-Hung Chen1, Yen-Hua Chang1,2,3, Alex Tong-Long Lin1,2,3, Kuang-Kuo Chen1,2,3
Department of Urology, Taipei Veterans General Hospital1; School of Medicine2 and Shu-Tien Urological Institute3, National Yang-Ming University, Taiwan
Introduction:
Metanephric adenoma(MA) is a rare neoplasm. It’s benign renal neoplasm originating in the epithelial cells of the kidney. Most tumors are asymptomatic, and incidentally discovered during examinations for other problems. It is difficult to distinguish metanephric adenoma from malignant neoplasms by image. It is often diagnosed by pathological report after surgical treatment. The present study reports the case of a 45-year-old female that presented with metanephric adenoma.
Case presentation:
A 45 years-old female had small renal mass over left kidney during evaluation of pancreas mass. Physical examination revealed no significant finding. Computerized tomography(CT) and Magnetic resonance imaging (MRI) revealed a neoplasm lesion localized in the left kidney without lymphadenopathy. Left partial nephrectomy was performed on December 23, 2015. Microscopic finding composed of monotonous tumor cells with few light pink cytoplasm, small, uniform nuclei and inconspicuous nucleoli, arranged in solid sheets, small acini, and papillary structure. Hyalinized stroma with focal calcification are also noted. The tumor cells are immunoreactive for Wilms' tumor antigen(WT1). The final pathological report revealed metanephric adenoma.
Discussion:
According the literature review, Metanephric adenoma (MA) is a rare benign tumor that accounts for 0.2‑0.7% of adult renal epithelial neoplasms. <200 cases have been reported in the literature. Peak age of MA was in the fifth or sixth decade of life. Most tumors are incidentally finding. Some patient will have flank pain, hematuria and palpable mass. Lab data may reveal polycythemia. MA cannot be easily distinguished from other malignant neoplasms using imaging alone. Macroscopic, MA appears as a well‑defined, round, solid, soft mass varying in size. Microscopic, MA expresses CK7 and WT1 and does not express epithelial membrane antigen or AMACR. Radical or partial nephrectomy may indicate for treatment due to the risk of malignancy without pathology.
Conclusion:
Metanephric adenoma is a rare benign tumor. It cannot be easily distinguished from malignant neoplasms of kidney by imaging. Metanephric adenoma can recognized by microscopy. Surgical intervention is suggested due to diagnosis is challenging without pathology.